This invention in general relates to a counterpulsation device that assists the pumping action of the heart and also increases the supply of blood to the heart muscle. Cardio-pulmonary resuscitation as now being taught for cardiac arrest, requires rhythmic compression of the chest with less frequent ventilation of the lungs by mouth to mouth breathing. One recent resuscitation device consists of a pneumatic garment that is rhythmically inflated to compress the torso while a tube in the windpipe periodically inflates the lungs. Though this provides excellent circulation of blood to the periphery during compression, there is inadequate circulation of blood to those organs within the zone of compression, including the heart muscle itself, which gets only slight perfusion during the diastolic period between chest compressions. This device may also be synchronized with a weakly beating heart to provide cardiac assistance.
Another group of cardiac assist devices work by counterpulsation. The first of these is the intra-aortic balloon pump. Its balloon is deflated during systole so as to drop the pressure in the aorta against which the heart pumps and reinflated during diastole (between heart beats) so as to raise the diastolic pressure which perfuses the heart muscle. Complications of this device include blood clots, bleeding, infection and sometimes loss of a leg. Therefore non-invasive counterpulsation devices have been developed which achieve the same effect by abrupt compression of the extremities so as to squeeze arterial blood back into the aorta during cardiac diastole then abruptly releasing the compression so as to drop the systolic aortic pressure against which the weakened heart ejects blood. Counterpulsation devices are of course useless during cardiac arrest.
Combining compression of the torso during cardiac systole with compression of the extremities during cardiac diastole has been proposed by some researchers, though such a device is not commercially available.
It is an object of this invention to provide a simple device that substitutes a vacuum around the torso for compression of the extremities. Thus, during cardiac arrest the negative pressure will draw venous blood into the lungs and the compression will pump oxygenated blood to the periphery. If synchronized with the weakly beating heart it will provide the same assistance as the combination of the two above devices, but in a much simpler, more compact and easier-to-apply form. It also ventilates the lungs without the need of an endotracheal tube.